The present invention relates to an electric ignition advance system for internal combustion engines.
Two types of mechanical ignition advance mechanisms, centrifugal and vacuum advance mechanisms, have been known in the art. The centrifugal advance mechanism controls the ignition timing of an engine by varying by centrifugal force the positional relation between the engine camshaft and the distributor cam lobes and the vacuum advance mechanism controls the ignition timing by moving the advancer rod in accordance with the degree of vacuum in the intake manifold and thereby rotating the breaker plate of the distributor.
However, since all of these conventional centrifugal and vacuum advance mechanisms are of the mechanical type, these mechanisms are much unsatisfactory in accuracy and it is difficult for them to meet the required ignition advance characteristics. Although electric ignition advance systems of various types have also been proposed, their application in practical use is still unsatisfactory due to such deficiencies as unsatisfactory accuracy, complicate circuitry, etc.